Chapter 6 | Tape format |
Track numbering
All even numbered tracks, and the Directory Track, are recorded in the forward direction (the direction from the BOT marker to the EOT marker). All odd numbered tracks are recorded in the reverse direction (the direction from the EOT marker to the BOT marker). All even numbered tracks are located below the Directory Track; all odd numbered tracks are above it.
Track format
Tracks are recorded sequentially beginning with track 0, then track 1, and so on. Before recording, data are grouped into blocks, and blocks are grouped into frames with 64 blocks per frame.
Two numbering methods are used for blocks: physical numbering and logical numbering. Both numbers start from 0 at the beginning of each partition.
Physical numbering is related directly to the recorded block on the tape. Each
new block is given a unique physical number, regardless of its contents.
Logical numbering does not relate to the blocks physically recorded on the tape; rather, this type of numbering is the block numbering system used by the host computer. Often the host system operates with logical blocks that are a different size from the
The host blocks can be larger or smaller than
The format provides both a physical block number for each block recorded on the tape and a logical block number that can span more than one physical block. These two numbers are recorded in the control field of every block.
Frames
Every track on the tape is recorded in blocks that contain 512 data bytes. The data bytes are
A frame is made up of 64
Page 64 | STT8000A Product Manual |
